The Doctor Who Oversaw the Creation of 3-Parent Baby Explains the IVF 'Breakthrough'

Illustration by Jim Cooke.

Dr. John Zhang of Manhattan’s New Hope Fertility Center has long performed miracles for fertility-challenged couples. In a typical year, his futuristic-looking clinic (its sleek all white-interior looks like something out of a 2001: A Space Odyssey-themed spa) oversees hundreds of births.

Zhang is responsible for creating the world’s first three-parent infant—a baby produced by combining a father’s sperm, a mother’s egg, and a donor egg.


The birth of the baby, formally announced this week in New Scientist, is a big deal in fertility circles. The technology Zhang employed to produce the three-parent baby not only provides a source of hope for couples looking to avoid passing deadly genetic disorders on to their offspring, but also, Zhang says, potentially ushers in an era in which more and more women in their 40s and 50s will be able to have their own biological children. Researchers additionally speculate the technology lays the groundwork for the possibility that same-sex male partners may one day be able to have biological children of their own.

The three-parent baby—a boy—was born at a Manhattan hospital in April to a couple who had worked for 20 years to start a family. The mother, from Jordan, is a carrier of Leigh Syndrome, which is likely to affect a baby’s developing nervous system. She and her husband lost two infants to the disorder, and miscarried four more, which is why she sought Zhang’s help.

New Scientist reports that a method of three-parent reproduction called “pronuclear transfer” is already approved in the UK:

[It] involves fertilising both the mother’s egg and a donor egg with the father’s sperm. Before the fertilised eggs start dividing into early-stage embryos, each nucleus is removed. The nucleus from the donor’s fertilised egg is discarded and replaced by that from the mother’s fertilised egg.


Because the couple is Muslim and didn’t want to destroy two embryos, Zhang and his team used a different method—they removed the cellular nucleus of the mother’s egg and inserted it into a disease-free donor egg which had already had its nucleus removed. Working in Mexico, the team then fertilized the new combination egg with the father’s sperm.

The procedure, Zhang said in an interview with Jezebel, essentially replaced the corrupted “egg white” of the birth mother with the healthy “egg white,” or mitochondria, of the egg donor, without altering the nucleus, or the “egg yolk” of the biological mother, which contains most of the genetic information responsible for determining a baby’s traits. According to New Scientist, five eggs were prepared using the new technology but only one was deemed suitable to fertilize.


“This is considered one of the latest and biggest breakthroughs in the IVF [in vitro fertilization] world,” Zhang told Jezebel. “The first breakthrough in the world of IVF was the development of IVF itself, the second was the development of embryo freezing, the third is PGD, or genetic testing of embryos (where embryos are biopsied prior to transfer to determine whether they are healthy). And number four is ICSI, which enhances the ability of sperm (particularly in older fathers) to fertilize an egg.”

“This is number five,” Zhang said of the three-parent baby. “The principle we are applying is very different.”


Zhang chose to perform the controversial procedure in Mexico because the U.S. doesn’t currently authorize such reproductive methods, having deemed them potentially unsafe. After a successful embryo transfer, the couple later returned to New York, where a beaming Zhang was on hand in the delivery room, when the baby was delivered by Caesarean section this spring. The baby is being monitored closely.

“We still have a long way to go to follow up with the patient closely to ensure the safety of the procedure,” he said. But so far there are no signs of illness.


The parents, Zhang says, are overwhelmed by the media attention that the birth of their son has created and Zhang says it is now his mission to protect the privacy of the family as best he can.

“This is a very neat technique and it’s amazing and we still can’t believe we made it,” he said.


Zhang says he shies away from using the term “three parent baby” to describe the newborn, arguing that the term, while he says is “sexy” to the media, perhaps places too much emphasis on the role of the egg donor.

“A parent is someone who educates and molds a child,” he continued. “It’s a matter of opinion, but I think it’s the two parents who are raising the child who should be called parents.”


Zhang had intended to wait until late October to announce news of the three-parent baby’s arrival at a meeting of the American Society for Reproductive Medicine in Salt Lake City, but on Tuesday, New Scientist broke news of Zhang’s paper which documented the birth.

Within hours, Zhang was inundated with media requests from around the world, ranging from Nature to the New York Post. Long after his office had closed Tuesday evening, Zhang—who went to medical school in China and has been pioneering IVF techniques for more than two decades—was fielding calls from the BBC as he struggled to go over patient charts.


Zhang says he is cautiously optimistic about this first “miracle” baby and what he says it could mean for infertile couples. He says it’s not inconceivable to think that three-parent babies could eventually become an offering at the nation’s leading IVF clinics.

But he says there is much more research and testing to do. The procedure won’t be regularly available to most families in the U.S. until it has undergone clinical trials to make sure it does not harm a pregnant woman and that a baby can be born safely.


Unsurprisingly, the procedure is attracting its fair share of controversy. Critics worry it continues the ongoing trend towards ‘designer’ babies, and pro-life advocates fear the procedure will result in the disposal of a growing number of fertilized embryos.

Zhang’s success is, of course, not without precedent: A U.S. based doctor, Jacques Cohen, developed a previous three-parent fertility method in the 1990s, according to the BBC, creating 17 babies using the technique. But some of the fetuses resulting from the technique were missing X chromosomes and at least one child showed signs of a development disorder, prompting the FDA to ask clinics to stop using the technique.


Still, Zhang’s development of the new three-parent-baby technology is exciting for fertility-challenged women, particularly those ages 35 and over. The leading cause of miscarriage among women of advanced maternal age is ‘aging’ eggs, in which the mitochondria is corrupted. But Zhang’s method—replacing a woman’s mitochondria with donor mitochondria—solves that problem, meaning more and more women in their 40s and 50s will potentially be able to have biological children of their own.

The new technology, as also previously mentioned, could also hold potential for same-sex couples hoping to reproduce. Using donor egg mitochondria, scientists have been able to produce offspring in mice, parented by two males, although it remains to be seen whether that can be replicated in humans.


How soon could we see the first three-parent baby produced by two male humans, with the help of a donor egg’s mitochondria?

Zhang won’t put a timeline on it. What he will say is this: “Whether it can happen with humans, you have to leave it to your imagination.”


Mary Pflum Peterson is a multi-Emmy-Award-winning producer who has spent years covering parenting and fertility stories. She is additionally the author of the New York Times bestselling memoir, White Dresses: A Memoir of Love and Secrets, Mothers and Daughter.

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